| In the planning of water-saving irrigation and the evaluation of comprehensive effects of water-saving irrigation projects, much stress has been placed on the balance and coordination between technological objectives and economic objectives, which are known as the technology-economics principle. The evaluation scale is often confined to specific irrigation projects, whereas a comprehensive evaluation method on a regional scale is yet to be developed. Trying to solve this problem, guided by the principle of region wide sustainable development, partly based on the research assignment for The National Water Saving Irrigation Tenth Five-Year Plan and the Development Programme for 2010 and "the development and industrialization of efficient-agriculture-water-use material and equipment and the establishment of the technological service supporting system" which is a part of the national science-technology industrialization key project "Efficient Agricultural Water Use Science-Technology Industrialization Demonstration Project", thedissertation makes a systematic study-covering concept, theory and application,through analysis, calculation and comprehensive evaluation-of the comprehensive effectevaluation indicators of water saving irrigation on a regional scale and the afterevaluationmethods and their application.The results of the research are as follows:1. The concept of sustainable development is incorporated into the connotation of water-saving irrigation.Water-saving irrigation is the general term for all the technological measures taken, according to the law of crop water demand and the condition of local water supply, with the smallest possible input of water, to achieve the optimum comprehensive effect in economic benefit, social benefit and ecological and environmental benefit. The technological integration of various water-saving irrigation techniques which are suited to the local conditions and help to achieve the goals in irrigation-water saving can be termed water-saving irrigation technological system. This system generally comprises water-source tapping and optimal utilization technology, water-saving irrigation engineering technology, water-saving and efficient agronomic techniques, and water-saving irrigation management techniques.2. The concepts of "flexible water-saving" and "inflexible water-saving" are advanced, and the water-saving and production-increasing potentialities in Northern China are calculated.On the theoretical basis of water-saving irrigation-including systematics, biology andphysics-an analysis is made of the likely wastage nodes of irrigation water in the whole process of irrigation-starting from the water source to the uptake and utilization by the crops. In view of the two different cases, namely, sufficient water supply and insufficient water supply, the concepts of "flexible water-saving" and "inflexible water-saving" areadvanced. The water-saving and production-increasing potentialities in Northern China are calculated. A basis for decision making in water saving irrigation development is provided for the departments concerned.3. The composition of the comprehensive technological system of water saving irrigation is analyzed.To meet the requirement of sustainable development, the comprehensive technological system of water saving irrigation is divided into four subsystems. The relationship between them is analyzed. A foundation is laid for the formulation of comprehensive effect evaluation indicators of water-saving irrigation.4. The zoning method for water-saving irrigation is studied.In view of the characteristics of water-saving irrigation, a synthetic zoning method for water-saving irrigation and the zoning indicators are advanced, which integrate the strong points of both fuzzy clustering and principal components analysis. The corresponding computer program is written. The calculation is simplified by applying principal components analysis, i.e., by processing the zoning indicators by means of reduction of dimens...
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